One of the best $100 I've ever spent
I have four year old twin boys, and we have had an annual pass to the San Diego Zoo and Wild Animal Park ever since they were born. We have a dual membership, which allows unlimited access to two adults. The membership costs $99 and is good for unlimited access to both the Zoo and Wild Animal Park. The annual membership also comes with two free guest passes (which come in handy when family comes to town), and free passes on the Wild Animal Park tram and the Zoo Skyfari. After the boys turned three years old, we had to get them their own passes, which are about $30 each.
The boys love to go the the zoo and the wild animal park, and we get a lot of use out of the passes. One of our favorite things to do at the Wild Animal Park is to visit the Lions. It is best to do that first thing in the morning, as that is when the lions are the most active.